Selective layering of products such as cases of beer bottles, cans, crated produce and other such items is a common occurrence during the assembly and preparation of a shipment of goods to consumer distribution points. A notable example may be seen in the brewing industry where a final product in the form of bottled beer packaged in corrugated paper containers is shipped to various distribution centers under a variety of labels, different brands and the like. This is a frequent occurrence particularly amongst smaller distribution centers, including taverns, hotels and restaurants which are most likely to call for a mixed variety of beer products.
The distribution of farm or grower produce is another good example. Thus, a palletized shipment of fruit may include a number of individual or mixed layers of crated citrus fruits, non-citrus fruits, vegetables and the like.
Varying pallet orders of the aforementioned types can be manually assembled by individually selecting various containers or packages of a desired product and hand stacking the packaged products onto a selected order pallet. This procedure, however, is both time consuming and ergonomically inefficient and difficult.
In recognition of this problem, various stacking and clamping devices have been developed to provide selective layering of the aforementioned packaged goods. Under ideal conditions, manual handling is eliminated by selecting individual layers of packaged products and selectively layering individual product layers to form a picked order pallet. A typical example of such apparatus is disclosed in U.S. Pat. No. 5,516,255 Tygard which describes clamping apparatus utilized in connection with a forklift truck for lifting objects arranged in layers comprising both square and elongated rectangular objects. The apparatus comprises two pairs of clamps positioned in mutually orthogonal relation and which are actuated by an obstructing overhead-positioned hydraulically operated arrangement of cylinders and pistons. A second disclosed embodiment utilizes only a single pair of clamping arms and may be employed where a plurality of objects are rigidly interconnected or where only a single object is required to be lifted. The clamping apparatus is utilized to grip the object while a forklift truck raises the gripped object for placement upon a picked order pallet.
An anticipated problem with the Tygard device, as well as other such selective layering devices, is found in the obstructing overhead operating mechanism used to actuate oppositely positioned pairs of clamps. Such an overhead clamping mechanism limits the apparatus to picking up only a single layer of preassembled objects and at most only two layers provided that sufficient overhead clearance is present. A general limitation of such apparatus is therefore an inability to stack more than two layers at a time when assembling a picked order pallet of work products or objects.